


Firsts

by Marcanine



Category: Undertail - Fandom, Undertale (Video Game)
Genre: Bara Sans, Big Sans, F/M, First Times, Fluff, Fluff and Smut, NSFW, Praise, Size Difference, Smut, Virginity, reassurance, slight cum kink at the end there?
Language: English
Status: Completed
Published: 2016-03-21
Updated: 2016-03-21
Packaged: 2018-05-28 02:00:36
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,184
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6310630
Author URL: https://archiveofourown.org/users/Marcanine/pseuds/Marcanine
Summary: <blockquote class="userstuff">
              <p>
  <i>“don’t really know what i’m doin’, but i did my research. google’s a great thing, babe.” </i>
</p><p>
  <i>You couldn't help but giggle at that.</i>
</p><p>this was a request from tumblr. you bone the skele.</p>
            </blockquote>





	Firsts

**Author's Note:**

> _Anon here Can I request some female anon first time x sans?_
> 
>  
> 
>  
> 
>  
> 
> _Oh my, I feel so embarrassed right now... Can I request something with really smol reader, like, about 5' tall. The first time, maybe, not in general with Sans (Underfell or not) in particular, how they're shy and unsure at first but then relax and go into very thoughtful lovemaking with surprise natural skillfulness in kissing, licking and all the tongue action._
> 
>  
> 
> these were a few requests from my tumblr! feel free to join the sin at http://bonethot.tumblr.com

“_____?”

The sudden call of your name causes you to jump and stare at your intruder. Leaning against the doorway was Sans, the light of your hallway cascading through your boyfriend’s ribs like a sunset through blinds. It struck you he was shirtless and you felt the need to cover your eyes. 

“nervous?” He asks, entering your bedroom and gingerly closing the door behind him. He comes to sit on the bed beside you, a large hand resting on your bare thigh as you look away in shame. “s’alright. i am too. we don’t need to do anythin’ you ain’t ready for.”

“No, no. I want this,” you reassure him, suddenly sad as your hands clasp over his larger one. “It’s just…the pain is scary, and I don’t wanna disappoint you.” 

His hands drag up the curve of your half-naked body, cupping your face and turning you to him. He runs a thumb over your lips onto your cheek, wiping a tear you didn’t even know you shed. His fangs were slightly dripping saliva in his need. 

“shh, baby,” he coos, left arm snaking around you and pulling you into his shirtless frame. “you could never disappoint me. i’m kinda afraid of the same thing.” 

You nuzzle into his chest and his arms wrap around you. He starts to slowly rock the two of you, whispering reassurance into your ear and practically draining you of the self-doubt that was plaguing your mind seconds earlier. His touches grow more intimate as he gently cups your ass, pulling you closer to his frame as his fingers brush the skin under your belly button, teasingly. You begin to explore his chest, fingers sliding down his sternum and hooking into his ribcage as the grip on your lower back tightens ever so slightly. He lies down on your bed, dragging you down with him as he places a bony palm on your chest, slowly pressing you into the mattress. His frame dwarfed you whenever you stood side-to-side with him, and the size difference became much more apparent–you felt like a mouse now. 

He peppers your cheeks with toothy kisses as he gets on top of you, nestling between your legs, hands now resting on the clasp of your bra. The white lights of his pupils rest on your face, trying to pick up on any body language you express, unspoken words or pleas to stop. You muster up the courage to wink at him, and he chuckles, the rich laugh rumbling through his bones and tickling your skin.

“you’re so beautiful, ya know that?” His usually smug grin was so genuine and real that your heart melted. “i’m so lucky, so fucking lucky,” his warm phalanges unclasp your bra, and he slides it off of you, his eye sockets slowly widening as his pupils rake up your form. They dilate into the faintest little heart shapes as his fingers explore your skin. “fuck, you’re soft.” 

Despite all of the sweetness, you feel yourself growing wetter. You unconsciously rub your thighs together and his hands still your movements. 

“damn, is my baby girl needy?” He laughs at your embarrassment, tentatively dragging your panties down your legs, shooting you a smug expression as his hand cups your wetness. You gasp and slightly arch into the touch. Sans was a natural, it seemed, and you were so inexperienced…

Sans seems to sense your apprehension, and he leans down to nuzzle his skull into your neck, rubbing his hipbone against your core. 

“i’ll take care a’ya, i promise…” His low voice shifts into a growl as his jaw manifests with cyan light; the void of his throat becoming replaced with an electric blue tongue, flopping out and dripping with his trademark ectoplasmic saliva. “don’t really know what i’m doin’, but i did my research. google’s a great thing, babe.” 

You can’t help but giggle at that. The giant skeleton was most certainly not a virgin, but you were the first human he had ever been with, as well as the first meaningful relationship he’d ever been in. In the Underground, relationships went fast, as when monsters mated, they did so within days of the first date. Sans never clicked with anyone as much as he did you, and you were so thankful that he’d taken you on more than one date. Sans was too. 

His tongue suddenly runs along your bottom lip, begging for entrance. You part your lips and he practically lunges at you, thick tongue enveloping yours as he maintains control of the kiss, his bony hands grasping the back of your neck in wanton. The pair of you groan, happy to finally embrace each other on such an intimate level. 

Until now, your relationship with Sans had been lacking in the physical department, as both of you had been too apprehensive to initiate anything. A small reason was that yes, he was a skeleton, so  _obviously_  he wouldn’t have a penis, but it was more or less the fear of losing your virginity and letting him down. 

Your doubts begin to fade as Sans deepens the kiss, his slimy tongue delving behind your teeth, pleasantly cool around the edge of your throat. He coaxes a breathy moan from you as he pulls away, a thin trail of saliva connecting the two of you before breaking on your chest. 

That smirk is back on his skull as he moves to peck at your breasts, his smooth hands palming the left one as he licks a stripe up the right. His fingers clasp at your nipple and you squeak. He ceases his ministrations and makes eye contact with you, his eye sockets cutely furrowed in concern. 

“was that…a good sound?” 

“Yes,” you whine, laughing a bit at his worry. He was so sweet. “Please keep doing that.” 

“okay,” his pleasantly cool tongue returns, circling your nipple as he pinches the other one, your back arching into his touch. You start to pet at his skull, panting in need through his teasy touches. 

“Sans,” you rub your thighs together and he gets the hint. 

“mm, i’m comin’ babe,” he chuckles, tongue trailing down your torso painstakingly slow, before passing over your clit. 

You loudly moan before clasping your hand over your mouth, Papyrus was just downstairs! Propping yourself up with an elbow, you buck your hips into his mouth, tongue purposefully missing everything as he laps your thigh. He maintains eye contact as his phalanges rub at your folds, and your arm quivers, finding your body weak as he has you at his mercy. He raises them to his mouth and you shudder as he cleans them off with his tongue.

“S-Sans, come here,” you plead, and he obliges, licking his lips as he kisses you again, hungrier. His bony finger circles your entrance before pressing inside, practically without resistance from how turned on you were. You moan into his mouth, feeling every bump and ridge on his skeletal digit when it rubs against your walls, his knuckles colliding with your lips as it hilts. 

You attempt to grab at his vertebrae and pull him closer, but a sickening crack fills the room as your fingers accidentally collide with his ribcage on the way there. He immediately removes his fingers and leans up on his knees, left eye radiating cyan while he scans you for injury. You were surprised a skeleton could sweat that much. 

“god, baby, are you ok?” 

“Yeah,” you wince, “Just my fingers.” 

He grabs them and pulls them in front of his face, staring intently. 

“Sans, I’m fine. My joints just cracked.” 

He presses his teeth to them, inhaling gently as he laces them under his rib cage and around the back of his spine. “thank god. is that better?” 

“Yeah,” you smile, pulling him back into you. You jolt in surprise as his single finger is joined by another, slowly pumping in and out. You moan his name and he slightly speeds up, the pleasure growing steadily as your grip on his spine tightens. 

You bite your lip, eyes going wide and choking back a cry as he rubs against your spot, effectively curling your toes. His smirk becomes downright smug. 

“found it,” he sings, probing you again, drawing the same reaction from you as your orgasm starts to build. You wouldn’t last long. 

“Saaan-mmmfph-!” your call was muted from his tongue filling your mouth once again, swallowing your moans as his fingers become a blur. His knuckles brush against your clit and you break, orgasm washing over you as he deepens the kiss. You forget to breathe, body shutting down as you almost scream into his mouth, his fingers slowing down to help you through the aftershocks. He withdraws his tongue and groans, his pupils reeling back into his skull as your scent hits his nose, your heartbeat so violent he could  _hear_  it thumping against your chest. 

You take a moment to collect yourself, taking deep breaths as his bones quake on top of you. 

“that’s a good girl. you’re so fucking  _perfect_ , _____.  _so_  perfect, so beautiful and amazing,  _fuck_ , i need you, i really need you,” he ruts against your core, a glowing bulge shining through his shorts as it grinds against you, and you sharply exhale. He covers your face and chest in toothy kisses, vigorously giving affection everywhere he saw fit. His bones continued to quietly rattle as he took in your form; flushed face, out of breath, stray hairs sticking to your forehead, sweat trailing down your curves and into the bedsheets.

His fingers timidly squeeze and rub at your thighs, half-lidded eyes expressing all of the need he felt, but would never act upon without a green light.

“Sans,” you sigh. “What if it hurts? I’m…I’m scared,” 

“no, no no no baby, i’d never hurt you. it might sting a bit, but…” His fingers stroke your hair as he gazes down at you, lovingly. “we can stop whenever you want to. ‘m never gonna pressure you into somethin’ like this. i’m happy the way things are now.” 

You absentmindedly run your fingers along his arms, heat flourishing in the pit of your stomach as soon as you think about how good it would feel to take this step with him, to be reassured that he loved you, to be filled by Sans, your sweet, considerate, goofy Sans. Your legs open and you gently tug on his spine, his eye sockets widening in slight disbelief as you press a kiss above his nose-hole. 

“I want it,” you breathe in between kisses, “I want you too, Sans, I really do.” 

He lets out a relieved breath. “we’ll take it really slow. i’m gonna make you feel so good,” his growl returns and you whimper, your core flaring back to life as he leans down to lick and nibble at your collarbone. 

He suddenly raises himself to his knees, the cyan fire of his magic illuminating his left eye as his ribcage pulses with arcane light. You gasp as his blue aura slides down his spine, so sensual that you couldn’t look away if you wanted to. It drifts to his pelvic bone, magic wisps solidifying into an ectoplasmic tendril, similar to his tongue. He grunts and it thickens, elongating into a phallic shape, small bumps running along the shaft, akin to a ribbed toy. It was a few inches above average length, with intimidating girth. He sheepishly rubs the back of his skull, looking anywhere but at you. 

“uh, what do ya think?”

“Sans,” you giggle, “It looks almost exactly like that sex toy we saw at the mall.” 

A deep blush envelops his skull so quickly that you blinked, and suddenly he was a blueberry. 

“y-yeah. i worked hard on it. the one we saw at the store said ‘good for beginners,’ and i thought you would like it. we could…i can change it, if you don’t like it. i wouldn’t blame you, i mean, it’s kinda bad anyways-”

You silence him when you roll onto your knees and press your lips to his teeth, boldly grasping his length with your fingers. It was warm and slick to the touch, much like his tongue, yet slightly firmer. He groans as you run your fingers along the bumps, and as you experimentally rub the head with your thumb, he chokes, thrusting into your hand. 

“I love it. Thank you, Sans.” You lean up to kiss the underside of his skull, before releasing him and lying back down on the bed. He darts down to kiss you, tongue snaking back into your mouth with such a passion that it almost brings a tear to your eye. 

You feel him push at your entrance as he breaks the kiss. His eyes were closed in intense concentration and his massive hands threatened to tear out chunks of your mattress with how hard he was gripping it. 

He starts to push in and you immediately feel the burn, your body instinctively clenching around him as you whimper his name. He enters you at a snail’s pace, hushing you with kisses and nibbles at your neck to distract from the pain. You knew it was inevitable, but Sans had found a way to make it so much easier to endure. 

He deeply exhales against your neck, shaking in restraint, pausing halfway and allowing you to gather yourself before pressing forward. You press a kiss to his neck to urge him on, the plates of his spine rattling in response. That must have been a sensitive area. 

He continues to move, his length quelling the empty ache you had built up through all of the foreplay. He thrusts a little too quickly and you jolt, the sharp pain catching you off guard and you mewl into his shoulder. He immediately slows, whispering apologies, soothingly rubbing your scalp with his hard fingers. He grunts as his pelvis rubs against your crotch, hilting himself. 

“M-move, please, Sans,” you scrabble at his ribs for purchase, already feeling overwhelmed. He complies, pulling out halfway before pushing back in, his slow pace leaving a delightful burn along your walls. The initial agony of being penetrated for the first time blossoms into a deep, full-body pleasure that you could even feel in your fingertips. His cock spurts a bit inside of you, his sticky precum acting like a magical lubricant. 

“so tight,” he groans, “so  _fucking_  tight, baby, you’re so sexy,”

Your face heats up at his praise, the drag of his cock driving you insane as he pulls nothing but pleasure from your frame. High-pitched moans escape you with every thrust. You wanted more, no, needed more, you needed him more than anything in your life. 

“Sans,” you moan, and he visibly shudders at your tone. “Please, move faster, n-need more.” 

A particularly rough thrust causes you to cry out, toes curling in satisfaction as his speed increases, lewd sounds of your wetness filling the room. Your nervousness melts away along with the pain as his hand trails down to play with you, the other gripping your ass as he pulls you back onto his length. 

“ _yes_ ,” he growls, fangs elongating as his smirk twists into a carnal grin, cyan drool escaping the corner of his mouth. “i’ve been waitin’  _so long_  to hear you like this, baby.” 

“Ahhn, Saaaans!” You cry into his shoulder, and he moves faster, the head of his cock hitting you just right and white stars cloud your vision. 

“ _thaaat’s_  it, ______. you gonna cum?” He grunts, face flushed a brilliant shade of blue as he grabs your leg and throws it over his shoulder, his cock reaching even deeper inside of you, and it takes all of your willpower not to scream at the new angle. 

“N-no, Sans, Saaaahhnns,” you could barely speak, your thoughts filled with nothing but your bony lover, his glowing eye and dripping fangs, massive tongue hanging between his teeth and dripping fluid onto your chest, the pure hunger on his face setting your nerves on fire. You didn’t want to come yet, he hadn’t even finished once, and you thought that would be unfair. You feel your orgasm approaching fast nonetheless. His fingers circle your clit, occasionally rubbing and tweaking it, and you begin to drool. 

“ _mmm_ , fuck yeah, let it go baby, please cum for me,  _please_ ,” he begs, his hard fingers raking down your sides, squeezing at your hips as he pounds into you with abandon. “come on, babe, cum on my cock, you fuckin’ tease, m’gonna fill you up, gonna make my little baby  _scream_ –” 

You can’t hear the rest of Sans’ filthy talk as euphoria washes over you, clamping down on his length, legs shaking, screaming into your hand while tears fill your vision. Your orgasm hits you much harder than you anticipate, your back arching so far it cracks, his massive hands enveloping your sides as he grinds into you. He shouts his pleasure, the sudden tightness on his length causing him to shoot inside you with a roar, his hot magic coating your insides and spilling around his cock. His massive frame quakes above you as he pulls out, his shaky exhale upon witnessing his cum ooze out of you mixing with your pants of exhaustion. 

You tiredly smile up at him and he practically collapses next to you, a thick, bony arm wrapping around you and pulling you into his warm ribcage. Despite being made of bone, Sans was rather comfortable, even if you practically broke your hand on it moments ago. 

“that was…”

“Amazing,” you finish his sentence, nuzzling into him, feeling even smaller as he practically curls around you. 

“yeah, it was.”

The two of you lay in silence, breathing heavily. 

“Was…was it good for you?” You ask, nervousness returning once you consciously realize that you just had sex with your boyfriend. 

The white pupils of his eyes shift into tiny blue hearts. “good? that was  _incredible_ , baby. you sure you’re a virgin?” 

You snort at that, shoving his arm, and he laughs with you. Relief floods your mind as you contemplate cleaning up. 

“We should shower,” you sigh, making a move to get off the bed, before being tugged back into his arms. They snake around you tighter, and you groan. 

“uh-oh, babe. looks like my joints are lockin’ up again.” He playfully rubs his skull against your cheek and you do everything in your power not to cave. 

“Sans, nooo~,” you whine, “We need to shower.” 

“mm, can’t hear ya, don’t have ears.” 

“Sans…” 

“you’re so soft, baby.” 

“Sans!” 

“i love you.” 

Your protests die altogether, the confession shutting you up. It was the first time he had ever said it. 

“Sans…” you begin, through watery eyes. “I…I love you too.” 

A snore is all that answers you. He’d already fallen asleep!? 

“Bonehead,” you mutter, a smile glued to your face as you lean into him further, drifting off into the most peaceful sleep in your life. Chiding him would have to wait.

**Author's Note:**

> this was a lot of fun to write because i like. never write fluffy smut lol
> 
> thank u for reading <3
> 
> ...promos myself
> 
> http://bonethot.tumblr.com


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